Sony DT 18-250mm f/3.5-6.3 - £470
Noticeably smaller and nearly 200g lighter than the Sigma equivalent, the Sony 18-250mm lens makes a compact travelling companion. Part of the weight saving is due to the absence of an optical stabiliser, because it relies on sensor-shift stabilisation in Sony bodies.
Like the Olympus 18-180mm lens, the anti-shake performance didn't quite match optical stabilisation, giving between two and three stops of benefit. Considering the maximum aperture is f/6.3 at the longest equivalent focal length of 375mm, you'll find yourself frequently reaching for the camera's ISO button for faster shutter speeds.
There's little in the way of advanced features, although you at least get a basic distance-scale printed on the focus ring, and there's a zoom lock. The latter is hardly necessary because the lens is remarkably free of zoom creep.
Optical quality is a mixed bag. The Sony lens is sharp at the centre of the frame throughout its whole zoom range, but edge sharpness is disappointing. Colour fringing at the edges of the frame is very well controlled for an 18-250mm lens, at least from the wide end of the focal range up to 200mm. Fringing only becomes really noticeable beyond this point. Distortion was more of a problem, with extreme barrel distortion at the wide-angle end.
Considering the price, and the lack of an optical stabiliser or ultrasonic autofocus, we'd expect the Sony to deliver a bit more.
Sharpness test
Centre sharpness at all focal lengths is excellent, but it falls sharply towards the edge at the middle and longest focal lengths.
Fringing test
At the centre of the frame, fringing is minimal, but there's blue fringing at the frame edges at the extreme ends of the focal range.
Distortion test
Barrel distortion at 18mm is the highest in the test. At other focal lengths, it drops and changes to pinch distortion at the long end.
Image test verdict
The Sony produces the best results for centre sharpness. However, it drops dramatically towards the edges. Distortion at 18mm is also very high.
Score: 3/5
